1. Field of the invention
The present invention relates to a device and a method for adjusting parallax, an imaging apparatus, and an image reproduction device which are used for image capture and reproduction of stereoscopic images.
2. Description Related to the Prior Art
Digital cameras (hereinafter referred to as the 3D cameras) which are used for producing stereoscopic images are known. The 3D camera has a pair of left and right imaging sections. The imaging sections capture images of a subject simultaneously from respective left and right viewpoints. Thereby a left viewpoint image and a right viewpoint image are obtained. The left viewpoint image and the right viewpoint image constitute a parallax image. The 3D camera is provided with an LCD for displaying a reproduced or captured parallax image. The LCD displays a through image during imaging. Of the parallax image displayed on the LCD, the left viewpoint image is observed with the left eye of an observer and the right viewpoint image is observed with the right eye of the observer. Thereby, the parallax image is viewed stereoscopically.
It is easy to stereoscopically view the parallax image when the subject to be viewed has small parallax. As for methods for adjusting parallax, methods for changing the inclination of an optical axis of an imaging system and thereby increasing or reducing a convergence angle and methods for shifting a viewpoint image and thereby increasing or reducing the convergence angle are known (for example, see Japanese Patent Laid-Open Publication Nos. 08-251625 and 10-155104). For example, there are methods for translating image sensors and methods for translating cut out regions, which are cut out from the captured images to be used as the viewpoint images.
A minimum unit of a shift amount for shifting the viewpoint image at the time of the image capture is a pitch of pixels (light receiving elements) on a light receiving surface of the image sensor. However, a change in a distance (hereinafter referred to as the convergence point distance) to a convergence point at which the parallax is “0” is not constant even if the shift amount of the viewpoint image is increased or reduced by one pixel. The greater the convergence point distance, the greater the change amount of the convergence point distance relative to the shift amount of one pixel. The smaller the convergence point distance, the smaller the change amount of the convergence point distance relative to the shift amount of one pixel. Hence, when the shift amount of the viewpoint image is increased or reduced, for example, by a unit of pixel while a parallax image on an LCD or the like is viewed stereoscopically, stereoscopic effect of the parallax image being observed may be changed abruptly on a far distance side even if the viewpoint image is shifted based on a constant operation amount. The operation amount on the near distance side significantly differs from that on the far distance side, so that the observer may feel discomfort with a change in display in response to the operation and the operation may become difficult.